text: # Copyright (c) 2012 OpenStack Foundation
  # Copyright (c) 2012 Cloudscaling
  # All Rights Reserved.
  #
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  from oslo_log import log as logging
  
  
  from nova.scheduler import filters
  from nova.scheduler.filters import extra_specs_ops
  from nova.scheduler.filters import utils
  
  
  LOG = logging.getLogger(__name__)
  
  _SCOPE = 'aggregate_instance_extra_specs'
  
  
  class AggregateInstanceExtraSpecsFilter(filters.BaseHostFilter):
      """AggregateInstanceExtraSpecsFilter works with InstanceType records."""
  
      # Aggregate data and instance type does not change within a request
      run_filter_once_per_request = True
  
      RUN_ON_REBUILD = False
  
      def host_passes(self, host_state, spec_obj):
          """Return a list of hosts that can create instance_type
  
          Check that the extra specs associated with the instance type match
          the metadata provided by aggregates.  If not present return False.
          """
          instance_type = spec_obj.flavor
          # If 'extra_specs' is not present or extra_specs are empty then we
          # need not proceed further
          if (not instance_type.obj_attr_is_set('extra_specs')
                  or not instance_type.extra_specs):
              return True
  
          metadata = utils.aggregate_metadata_get_by_host(host_state)
  
          for key, req in instance_type.extra_specs.items():
              # Either not scope format, or aggregate_instance_extra_specs scope
              scope = key.split(':', 1)
              if len(scope) > 1:
                  if scope[0] != _SCOPE:
                      continue
                  else:
                      del scope[0]
              key = scope[0]
              aggregate_vals = metadata.get(key, None)
              if not aggregate_vals:
                  LOG.debug("%(host_state)s fails instance_type extra_specs "
                      "requirements. Extra_spec %(key)s is not in aggregate.",
                      {'host_state': host_state, 'key': key})
                  return False
              for aggregate_val in aggregate_vals:
                  if extra_specs_ops.match(aggregate_val, req):
                      break
              else:
                  LOG.debug("%(host_state)s fails instance_type extra_specs "
                              "requirements. '%(aggregate_vals)s' do not "
                              "match '%(req)s'",
                            {'host_state': host_state, 'req': req,
                             'aggregate_vals': aggregate_vals})
                  return False
          return True
  